May said she was concerned about the risk of injury to the
public, adding that they were likely to damage the reputation of
the police force. She said that the decision to use them was a
“serious” one and that a study had already been carried
out to assess their safe use.

"Without safeguards they have the
capacity to cause harm,"she warned.

May added that she was “unconvinced” about the
“operability” of the cannons purchased by Johnson, which
are already 25 years old.

She concluded by saying that she had concerns about the
"potential impact of water cannon on public perceptions of
police legitimacy."

Shadow Home Secretary Yvette Cooper welcomed the decision, saying
the Home Secretary’s words were “exactly right.”

Johnson, however, was “disappointed” by the move, a
source told the BBC.

The source added that the Prime Minister, the Metropolitan Police
Commissioner and many Londoners were supportive of water cannons’
usage Scotland Yard would continue to train officers on how to
operate them.

In the UK, only Northern Ireland uses water cannons as a form of
crowd control. They were deployed most recently on Monday against
Loyalist demonstrators during July 12 celebrations.